314 



University of California Publications. 



[Geology 



The fossa of the pectoralis secundus is relatively small on 

 the sternum and, as prolonged upon the coracoid, occupies less 

 than half the width of the ventral face of that bone. 



The posterior margin of the sternum as preserved indicates 

 a rather open notch on either side, — a factor of great variability 

 even in the limits of a species at present. 



The carina is relatively low as nearly as can be judged. The 

 anterior margin is intact from where it bends upward from 

 the wide manubrial region to the most anterior tubercle of the 

 free carina edge (fig. 7). The anterior margin thus becomes 

 very thick, but this thickness diminishes gradually backward 

 instead of appearing as a pronounced welt upon the anterior 

 end of the keel. 



The coracoid and furcula are decidedly cathartid. The cora- 

 coid shows a wide sternal end tapering gradually to a compara- 

 tively narrow shank (fig. 8). The sternal facet occupies less 

 than two-thirds the total width of this end. The ridge of the 

 pectoralis seeundns comes down the coracoid and crosses its 

 sternal facet at a point more than two-thirds the length of the 

 facet from its manubrial limit, but such is the widening of the 

 coracoid base that the fossa of the pectoralis secundus occupies 

 less than half the width of the bone. The hyosternal apophysis 

 is thin and flat, with the sterno-coracoid tubercle but little re- 

 curved. On its dorsal aspect the base of the coracoid is com- 

 paratively little excavated. Its head region shows ' striking sim- 

 ilarity to that of Gymnogyps. The praecoracoidal process is a 

 little less pronounced, thus reducing somewhat the concavity of 

 the axial aspect of the head. The process is pierced by the 

 foramen of the supracoracoid nerve. 



The furcula (no. 12508) lacks the distal half of the right 

 clavicle and the scapular tuberosity of the left clavicle. There 

 are numerous pathological exostoses about the distal end of the 

 left clavicle so that the grosser characters alone are to be noted. 

 Considering the great spread of the extremities of the arch, the 

 shaft of the clavicle seems rather more slender than in Cathartes. 

 Its cross-section is a little more rounded. The region of sym- 

 physis presents practically the same appearance as in Cathartes. 

 The angle of divergence of the two clavicles is very much greater 



